In a radio communication system, in which a communications node establishes and maintains contact with a plurality of subscribers, it is desired to transmit energy to and receive energy from only those areas where subscribers are located. In a space-based communication system, where the communications node is an orbiting satellite, it becomes especially advantageous to control the direction to which receive and transmit antenna beams are pointed due to the need to maximize costly satellite resources. For this reason, in many space-based communication systems, digital beamformers can be used as a flexible means for generating receive and transmit communication beams. The use of a digital beamformer in such a system allows the communications node to generate beams which service subscribers located within specific areas on the Earth's surface and steer these beams as the subscribers move relative to the satellite. Beams can be created and collapsed according to the particular demand on the satellite communications node at any given time. In a low earth orbit satellite system, where the satellite moves with high velocity relative to a terrestrial-based subscriber, a digital beamformer allows subscribers to be tracked within the entire field of view of the communication satellite.
In future space-based communication systems which provide wideband communication services to earth-based subscribers, the antennas used to transmit to and receive signals from the subscribers are expected to require an increasing number of antenna elements. As the number of antenna elements increases, the associated digital beamformer requires a greater amount of primary power in order to generate both transmit and receive antenna beams. Even when a digital beamformer is generating very few transmit or receive antenna beams, the primary power demand can still be quite high. This inability to reduce the power consumption of a digital beamformer operating under nominally-loaded conditions makes size, weight, and cost reductions in the primary power generation system difficult to achieve. Consequently, reductions in the overall operating costs of the communication system are also difficult to achieve.
Therefore, what is needed are a method and system which will enable a communication satellite to reduce primary power required in a digital beamformer operating under nominally-loaded conditions.